[This information is from pp. 6-12 of The Influenza Pandemic of 1918-19 and How It Affected the City of Schenectady, New York by Alan Morris (Schenectady: Union College, 1986) and is reproduced here with the permission of the author. It is in the Schenectady Collection of the Schenectady County Public Library at Schdy R 974.744 Mor. Title inside cover is America and Influenza: The Pandemic of 1918-19 and How It Affected the City of Schenectady, New York.]

Influenza is caused by a virus from one of two main families, A and B. Although epidemics of these two strains frequently occur, only type A, for unknown reasons, is capable of producing pandemics the size of 1918's. Type B influenza causes what is generally known as the "common flu." A third family, type C, causes mild respiratory infections, and does not cause epidemics. The A and B families are quite similar in structure. The virus is approximately 4-millionths of an inch in diameter, and is round but maybe slightly elongated. The surface of the virus is studded with spikes, composed of proteins, which contain small amounts of complex sugars. A protein matrix, or superstructure, gives the virus its shape. (See figure 1) Within this matrix is found the genetic material of the virus, RNA. (1)

The virus has the "ability" to change its virulence, which can result in either milder or more severe epidemics. The mutation of the RNA allows for the changing strength of the virus. The actual purpose of these mutations, as with any living species, is to enable the further existence of the virus. The results of these genetic changes are different spike patterns which enable the virus to overcome previous immunity or vaccination of its host population. (2) As a consequence of mutation, both types A and B contain hundreds if not thousands of different strains, many which are capable of causing an epidemic.

Human attempts to find the cause of influenza go back as far as the earliest records written about the disease. Heavenly bodies, such as comets, planets, stars and meteors have all been accused of causing influenza epidemics. In addition, the disease has been attributed to a poisonous gas that is supposedly ejected into the earth's atmosphere by volcanic eruptions and earthquakes. (4)

Robert Johnson, while writing about the 1793 influenza epidemic in Philadelphia, was the first to postulate that the disease was "propagated at least to some extent by contagion." (5) Most people, however, did not believe that influenza was caused by a specific contagion, and as late as 1894, scientists such as the British epidemiologist Charles Creighton did not believe that influenza was spread by a contagion, as stated by the germ theory. (6)

The influenza pandemic of 1889-90 set off a great crusade to find the cause of influenza. Viruses had not been discovered, and therefore the reseachers concentrated on finding a bacterial cause. In Germany, Dr. Richard Pfeiffer discovered that a certain bacterium was present in the throats of a great many influenza victims. Although it is called the "Pfeiffer influenza bacillus," there was no hard proof that it actually caused influenza. (7) The 1918-19 pandemic confirmed that even through it was present in many cases, "Pfeiffer's bacillus" was not the cause of influenza: "Attempts were made to determine whether it was really the cause of influenza by placing drops of cultures in the noses of volunteers. Usually these inoculations had no effect…" (8)

The scientists of 1918 knew that microbes smaller than bacteria, called "filterable viruses" because they could pass through filters that bacteria could not, were the cause of some diseases. However, the microscopic technology of the time did not permit the visualization of these viruses. (9)

The first reliable evidence that a virus was the cause of influenza was published in 1931 by Richard Shope of the Rockefeller Institute. He had inoculated pigs with unfiltered material and reproduced the disease. The breakthrough occurred when the pigs got sick from material that had been carefully voided of all bacteria. (10)

During the influenza epidemic of 1933 in London, the National Institute for Medical Reseach asked its scientists to make another attempt to isolate the cause of influenza. Three of these men, Smith, Andrews and Laidlaw, first isolated type A influenza in 1933. (11) This breakthrough aroused so strong an interest to capture and study the strain responsible for the 1918 pandemic that scientists exhumed the bodies of Alaskan victims in hope that the virus had survived and could be isolated by the new techniques. After this attempt proved unsuccessful, researchers turned to serological investigations to reconstruct the antibody patterns in the blood serums of survivors and thus find the antigenetic "fingerprints" characteristic that particular strain.

These studies concluded that the 1918 virus had antigenetic characteristics unknown before 1918, and found only in swine since the the late 1920's. This data led to the hypothesis that the killer strain may have been a mutation of a type A Swine Influenza that eventually lost its ability to spread from human to human. (12) The actual strain of the pandemic of 1918 was never isolated, and therefore its "identity" will never be positively known.

Although the influenza virus is constantly changing, the clinical disease produced remains relatively constant. (13) Influenza is an acute, highly communicable infection of the respiratory tract that is transmitted through droplet inhalation and mouthing of objects freshly contaminated by discharges from the nose and throat of infected persons. (14) The incubation period is short, usually only one to three days, and the course of the disease is highly variable, ranging "from a mild innocuous illness of short duration to one of great virulence ending in death." (15) In addition, many sub-clinical cases with symptoms resembling common colds, are known to affect the population.

Upon inhalation, the virus lodges itself in the upper respiratory tract of the victim, causing liquification of mucus, which prevents viral extrusion by ciliary action. (16) Next, the virus is incorporated into the surface cells of the respiratory tract where the RNA replicates and is released to attack other cells. Viral growth usually reaches its peak approximately 72 hours after it begins, and then declines rapidly. Under natural conditions, the time between the start of growth and development of symptoms is approximately 48 hours.

Chills, fever, headache, and muscular pain mark the onset of influenza. (17) As one Army medical officer noted during the epidemic, nearly all cases had the same symptoms:

The men almost universally complained of headache, pains in back, arms, legs and bones, sore throat, tightness in chest and cough. Epistaxis [nose bleed] was frequent. A mild pectechial rash was sometimes seen on the forehead. Constipation was common, but other gastrointestinal symptoms were not often noted. The initial temperature ranged from 99 degrees to 106 degrees, the average being about 102 degrees. (18)

Other commonly occurring symptoms included nasal congestion, inflammation of the mucus membranes, conjunctivae reddening, swollen glands, photophobia and eye pains. (19) While these symptoms were common to both "normal" influenza and the 1918 version, during the epidemic, many were intensified.

The most ghastly of the symptoms of the 1918 pandemic, and one not present in normal influenza, earned the disease one of its nicknames, "The Purple Death." The disease produced a purple discoloration found on the face, chiefly around the lips, and sometimes covering other parts of the body. This color was due to a lack of oxygen in the tissues of these areas, a direct result of the lungs filling with fluid. By the time the purple color had set in, the patients were already drowning in their own fluid, a condition that almost certainly meant death would soon follow:

The purplish discoloration was an early omen of disaster… [patients] walked into the hospital… not critically ill, but on many was the telltale purplish color about the face. Then and there, the physicians in the admitting office knew that many such were doomed, and nearly all such victims proved the rightness of the physicians' prediction. (20)

The duration of normal influenza is usually five to six days, with convalescence lasting seven to ten days longer. (21) In severe cases, however, influenza can take one of two courses: acute inflammation of the lungs resulting in excessive fluid build up, and death within a few days, or more commonly, the development of bronchopneumonia on the fourth or fifth day followed by death or a long period of convalescence. (22) Pneumonia is the most common complication of influenza, and the influenza-pneumonia combination caused more deaths than influenza alone. (23) Other complications involved the circulatory and nervous system. Influenza can produce various cardiac complications, ranging from temporary irregular heart beat to inflamation of the heart muscles. Encephalitis and encephalopathy are rare complications usually found only in children. (24)

In 1918, there was little that medicine could do to lower the pandemic's mortality rates. After considerable experimentation, the physicians felt that there was no specific cure for influenza. They were right. Today, influenza is generally treated symptomatically. The discovery of antibiotics provided the only advantage modern medicine has over its 1918 counterpart. Antibiotics are highly effective in dealing with the secondary bacterial pneumonia which often develops with influenza. If antibiotics had been available in 1918 pandemic, the death rate would have been drastically reduced.

The lack of any universally accepted cure led to one of the strangest phenomenons of the pandemic: the flood of advice and cures that was sent to government offices and newspapers. Camp Sherman, an army base in Ohio, received "on a single day… more than 300 telegrams urging the use of various strange concoctions… [and] hundreds of letters extolling the virtues of one or more sure cures." (25) The suggestions of these letters ranged from placing a shotgun under the victim's bed so the "fine steel of the gun could draw out the fever," (26) to sweating continuously for one and a half hours or standing outside stark naked. Other letters recommended drinking hot water or solutions of either bicarbonate or citrate of potash. One woman suggested inhaling the vapors from a pepper stew. (27) Gradually, it became clear that the best treatment was bed rest, and by the end of the pandemic, this appeared to be the most commonly prescribed.